Tall Fescue Online Monograph

When greater daily animal responses are desired, it is critically important that the feed offered be high enough in nutritive value and consumed daily in sufficient quantities to provide the desired level of gain. In both grazing and conserved forage feeding systems, a key objective is to use plants with characteristics that will support the target feed intake and gain. In the early literature, tall fescue frequently was categorized as lacking palatability (Cowan, 1956) and being low in nutritive value (Crowder, 1955) or of low quality (Lassiter et al., 1956; Jacobson et al., 1957). An assessment of tall fescue strains showed that palatability differences were present, but there was little relationship between the quantity of forage available and its palatability (Buckner and Burrus, 1962). In a subsequent study, Craigmiles et al. (1964) reported a significant correlation between palatability and leaf size and texture (broad vs. fine leaf). Generally, they noted that broad and thick, coarse, leafy plants were preferred, and preference was attributed to forage that was more succulent and tender. In further evaluation with cattle, it was shown that the selected germplasm was more palatable than the naturalized or commercial cultivars available at that time (Buckner, 1960). Although tall fescue populations under evaluation were segregating for characteristics such as CP, silica, and total sugars, cattle showed no selection (at least with the preference procedures used) of one germplasm over another (Buckner et al., 1969). The extent to which the endophyte was present in the forages evaluated and the degree to which it might have played a role in animal evaluations remains obscure. Consequently, much of the early work addressing the topic of palatability of tall fescue lacks the data necessary for an appropriate interpretation and does not warrant further consideration.

More recent evaluation using E- tall fescue cultivars or germplasms [‘Barcel'; C1 and HiMag (a first generation and a second generation selection, respectively, for increased Mg and Ca; Mayland and Sleper, 1993); Kenhy; KY-31; ‘Missouri 96'; ‘Mozark'; and Stargrazer] demonstrated that heifers grazed these entries selectively, giving a ranking of: Kenhy > KY-31 > HiMag = Barcel = C1 = Stargrazer > Missouri 96 = Mozark (Shewmaker et al., 1997). These results indicated palatability differences among the eight entries tested. To remove possible effects of morphological differences among these entries on ruminant preference (Krueger et al., 1974), the same plots used in the study by Shewmaker et al. (1997) were cut and harvested as hay. The hay was reduced into 7- to 13-cm lengths and fed in palatability trials in confinement using sheep and goats. In general, animals ranked the palatability similarly among the entries in confinement and grazing. Selection among the entries was attributed, in part, to differences in soluble carbohydrates and CP (Burns et al., 2001).

The potential presence of the toxic endophyte in tall fescue complicates the discussion of tall fescue palatability relative to other cool-season grasses. It is necessary to keep the endophyte status in mind to evaluate tall fescue properly, in light of the novel endophytes with reduced production of alkaloids that are being developed and inserted into improved tall fescue cultivars. Such positive changes may extend the utility of tall fescue beyond the north-south transition zone of the United States and make it a cool-season species used more widely in production systems throughout the world where it currently is, or might be, adapted.